parsing is the process of analyzing a continuous stream of input (read from a file or a keyboard, for example) in order to determine its grammatical structure with respect to a given formal grammar. A parser is a computer program that carries out this task. The name is by analogy with the usage in grammar and linguistics. The term parseable is generally applied to text or data which can be parsed.
Parsing transforms input text into a data structure, usually a tree, which is suitable for later processing and which captures the implied hierarchy of the input. Generally, parsers operate in two stages, first identifying the meaningful tokens in the input, and then building a parse tree from those tokens.
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